Split band multichannel magnetic recording head having scaled reader widths

ABSTRACT

An apparatus, in accordance with one aspect of the present invention, includes an inner array of data transducers on a module, the data transducers of the inner array being aligned along a common axis that extends between distal ends of the module. Two outer arrays of data transducers are positioned to sandwich the inner array therebetween. Inner servo readers are positioned between the inner array and the outer arrays. Outer servo readers are positioned toward outer ends of the outer arrays. Widths of at least some of the outermost data transducers in the inner array are less than widths of at least some of the innermost data transducers in the inner array.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic heads for magneticrecording tape, and related systems.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various challenges rangingfrom the design of tape head assemblies for use in such systems todealing with tape dimensional instability. For example, increasinglinear bit density dramatically increases vulnerability to spacing loss.

Some of the difficulties encountered when attempting to increase thenumber of concurrent channels in heads to enable increase in data rateper unit of tape speed are as follows. Conventionally, added channelsare required to fit in the space between legacy servo readers to readand/or write within a single data band. This is done to preservebackward compatibility and ensure tape dimensional stability (TDS)problems do not increase. Thus, when channels are added to a given width(e.g., a data band width), the pitch between channels must be reduced.However, tighter pitch causes, for example, increase in crosstalkbetween writers, increase in writer coil resistance if thinnerconductors are used, difficulty in managing greater congestion in thewiring layers, higher operating temperature due to the increasedtransducer density as well as higher coil resistance in writers or dueto higher needed current due to removal of turns, etc. Moreover, asmagnetic media goes to smaller magnetic particles in an effort toincrease signal to noise ratio, more write flux is needed to penetratethe tape, which in turn requires generation of more field by the coils.

The quantity of data stored on a magnetic tape may be increased byincreasing the number of data tracks across the tape. More tracks aremade possible by reducing feature sizes of the readers and writers, suchas by using thin-film fabrication techniques and MR sensors. However,the feature sizes of readers and writers cannot be arbitrarily reduced.Factors such as lateral tape motion transients and tape lateralexpansion and contraction must be balanced with reader/writer sizes thatprovide acceptable written tracks and readback signals. One particularproblem limiting areal density is misregistration caused by tape lateralexpansion and contraction. Tape width can vary by up to about 0.1% dueto expansion and contraction caused by changes in humidity, tapetension, temperature, etc.

Thus, while the transducer array width does not change, the spacing ofthe data tracks on the tape will vary as the tape expands and contracts.Ideally, the reader track width would be as wide as the data track beingread; this would provide the best signal. However, sensor track widthscannot be made as wide as the data tracks, because the sensors wouldread adjacent tracks upon expansion or contraction of the tape and/ordue to lateral misregistration between tape and head. Accordingly,reader widths are currently designed to be substantially smaller thanthe data track width, and all readers in a given head have the sametrack width. The reader track width is selected to accommodate theworst-case scenarios, i.e., the designer takes into account maximumexpansion/contraction and lateral misregistration when determiningreader track width so that each sensor is over a given track at anytime. FIGS. 20 and 21A-21B represent the effect of tape lateralexpansion and contraction on reader position relative thereto. FIG. 20shows a head 2000 relative to the tape 2002, where the tape has anominal width. As shown, the readers 2004 are aligned with the datatracks 2006 on the tape 2002. FIG. 21A shows the effect of tape lateralcontraction. As shown, the outermost readers 2008 are positioned alongthe outer edges of the outer data tracks. FIG. 21B shows the effect oftape lateral expansion. As shown, the outermost readers 2008 arepositioned along the inner edges of the outer data tracks. Because allof the readers 2004 have the same width, the readback signal level fromeach reader will normally be the same.

SUMMARY

The apparatuses and methods presented herein address difficultiesencountered when attempting to increase the number of concurrentchannels in heads to enable increase in data rate per unit of tapespeed.

An apparatus, in accordance with one aspect of the present invention,includes an inner array of data transducers on a module, the datatransducers of the inner array being aligned along a common axis thatextends between distal ends of the module. Two outer arrays of datatransducers are positioned to sandwich the inner array therebetween.Inner servo readers are positioned between the inner array and the outerarrays. Outer servo readers are positioned toward outer ends of theouter arrays. Widths of at least some of the outermost data transducersin the inner array are less than widths of at least some of theinnermost data transducers in the inner array.

As described herein, the foregoing configuration of data transducersenables a variety of operations, including, in various aspects,transducing data in multiple data bands using the inner and outerarrays, operating on legacy media using the inner array, etc.

Moreover, the relatively smaller widths of the outermost datatransducers reduce misregistration of the outermost data transducers andthe data tracks being read when tape lateral contraction or expansion ispresent.

In one approach, the transducer widths progressively decrease from theinnermost data transducers to the outermost data transducers.

In another approach, the transducers are grouped into sets of greaterthan one transducer, the transducers in each set having widths that areabout the same in that set, wherein the widths decrease from theinnermost set to the outermost sets. Such an approach may be selectedfor processing considerations.

Similarly, in some approaches, widths of at least some of the outermostdata transducers in each outer array are less than widths of at leastsome of the innermost data transducers in each outer array.

A method, in accordance with one aspect of the present invention,includes passing a magnetic recording tape having a plurality of databands over a module having an inner array of data transducers on amodule, the data transducers of the inner array being aligned along acommon axis that extends between distal ends of the module. Two outerarrays of data transducers are positioned to sandwich the inner arraytherebetween. Inner servo readers are positioned between the inner arrayand the outer arrays. Outer servo readers are positioned toward outerends of the outer arrays. Widths of at least some of the outermost datatransducers in the inner array are less than widths of at least some ofthe innermost data transducers in the inner array. The method furtherincludes simultaneously transducing data on two of the data bands usingthe data transducers of the inner and outer arrays.

Any of these aspects may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects of the present invention will become apparent from thefollowing detailed description, which, when taken in conjunction withthe drawings, illustrate by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive system, inaccordance with one approach.

FIG. 1B is a schematic diagram of a tape cartridge, in accordance withone approach.

FIG. 2A illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head, in accordance with one approach.

FIG. 2B is a tape bearing surface view taken from Line 2B of FIG. 2A.

FIG. 2C is a detailed view taken from Circle 2C of FIG. 2B.

FIG. 2D is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one approach where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIGS. 8A-8C are schematics depicting the principles of tape tenting.

FIG. 9 is a representational diagram of files and indexes stored on amagnetic tape, in accordance with one approach.

FIG. 10 is a side view of an apparatus according to one approach.

FIG. 11 is a representational view of the arrays of the apparatus, inaccordance with one approach.

FIG. 12 is a representational view of the arrays of the apparatus, inaccordance with another approach.

FIG. 13 is a representational view of an inner array of the apparatus,in accordance with one approach.

FIG. 14 is a representational view of an inner array of the apparatus,in accordance with one approach.

FIG. 15 is a representational view of an outer array of the apparatus,in accordance with one approach.

FIG. 16 is a representational view of an outer array of the apparatus,in accordance with one approach.

FIG. 17 is a representational view of the apparatus of FIG. 10 in use,in accordance with one approach.

FIG. 18 is a representational view of the apparatus of FIG. 10 in use,in accordance with one approach.

FIG. 19 is a flow diagram of a method, in accordance with one approach.

FIGS. 20 and 21A-21B illustrate the effect of tape lateral expansion andcontraction.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred approaches ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general aspect, an apparatus includes an inner array of datatransducers on a module, the data transducers of the inner array beingaligned along a common axis that extends between distal ends of themodule. Two outer arrays of data transducers are positioned to sandwichthe inner array therebetween. Inner servo readers are positioned betweenthe inner array and the outer arrays. Outer servo readers are positionedtoward outer ends of the outer arrays. Widths of at least some of theoutermost data transducers in the inner array are less than widths of atleast some of the innermost data transducers in the inner array.

In another general aspect, a method includes passing a magneticrecording tape having a plurality of data bands over a module having aninner array of data transducers on a module, the data transducers of theinner array being aligned along a common axis that extends betweendistal ends of the module. Two outer arrays of data transducers arepositioned to sandwich the inner array therebetween. Inner servo readersare positioned between the inner array and the outer arrays. Outer servoreaders are positioned toward outer ends of the outer arrays. Widths ofat least some of the outermost data transducers in the inner array areless than widths of at least some of the innermost data transducers inthe inner array. The method further includes simultaneously transducingdata on two of the data bands using the data transducers of the innerand outer arrays.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the approaches described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the tape drive100. The tape drive, such as that illustrated in FIG. 1A, may furtherinclude drive motor(s) to drive the tape supply cartridge 120 and thetake-up reel 121 to move the tape 122 over a tape head 126 of any type.Such head may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various approaches. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thetape head 126 to be recorded on the tape 122 and to receive data read bythe tape head 126 from the tape 122. An actuator 132 controls positionof the tape head 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneapproach. Such tape cartridge 150 may be used with a system such as thatshown in FIG. 1A. As shown, the tape cartridge 150 includes a housing152, a tape 122 in the housing 152, and a nonvolatile memory 156 coupledto the housing 152. In some approaches, the nonvolatile memory 156 maybe embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred approach, the nonvolatile memory 156 may be aFlash memory device, read-only memory (ROM) device, etc., embedded intoor coupled to the inside or outside of the tape cartridge 150. Thenonvolatile memory is accessible by the tape drive and the tapeoperating software (the driver software), and/or another device.

By way of example, FIG. 2A illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2B illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2B of FIG. 2A. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2B on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used for trackfollowing, i.e., to keep the readers and/or writers 206 aligned with aparticular set of tracks during the read/write operations.

FIG. 2C depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2C of FIG. 2B. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative approaches include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative approach includes 32 readers per array and/or 32 writersper array, where the actual number of transducer elements could begreater, e.g., 33, 34, etc. This allows the tape to travel more slowly,thereby reducing speed-induced tracking and mechanical difficultiesand/or execute fewer “wraps” to fill or read the tape. While the readersand writers may be arranged in a piggyback configuration as shown inFIG. 2C, the readers 216 and writers 214 may also be arranged in aninterleaved configuration. Alternatively, each array of readers and/orwriters 206 may be readers or writers only, and the arrays may containone or more servo readers 212. As noted by considering FIGS. 2A and2B-2C together, each module 204 may include a complementary set ofreaders and/or writers 206 for such things as bi-directional reading andwriting, read-while-write capability, backward compatibility, etc.

FIG. 2D shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one approach. In thisapproach, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative insulating layer 236. The writers 214and the readers 216 are aligned parallel to an intended direction oftravel of a tape medium thereacross to form an R/W pair, exemplified byR/W pairs 222. Note that the intended direction of tape travel issometimes referred to herein as the direction of tape travel, and suchterms may be used interchangeably. Such direction of tape travel may beinferred from the design of the system, e.g., by examining the guides;observing the actual direction of tape travel relative to the referencepoint; etc. Moreover, in a system operable for bi-direction readingand/or writing, the direction of tape travel in both directions istypically parallel and thus both directions may be considered equivalentto each other.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The head assembly 200 includes two thin-filmmodules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a magnetic tape head 200 isconstructed, layers are formed in the gap 218 created above anelectrically conductive substrate 204A (partially shown), e.g., ofAlTiC, in generally the following order for the R/W pairs 222: aninsulating layer 236, a first shield 232 typically of an iron alloy suchas NiFe (−), cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), asensor 234 for sensing a data track on a magnetic medium, a secondshield 238 typically of a nickel-iron alloy (e.g., ˜80/20 at % NiFe,also known as permalloy), first and second writer poles 228, 230, and acoil (not shown). The sensor may be of any known type, including thosebased on magnetoresistive (MR), GMR, AMR, tunneling magnetoresistance(TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one approachincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyapproaches of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one approach of thepresent invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one approach, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by a skiving edge 318 of the leading module 302 has beenfound by experimentation to be sufficient to keep the tape adhered tothe tape bearing surface 308 of the leading module 302. A trailing edge320 of the leading module 302 (the end from which the tape leaves theleading module 302) is the approximate reference point which defines thewrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,transducers 322 may be located near the trailing edges of the outermodules 302, 306. These approaches are particularly adapted forwrite-read-write applications.

A benefit of this and other approaches described herein is that, becausethe outer modules 302, 306 are fixed at a determined offset from thesecond module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one approach, the second module 304 includes a pluralityof data and optional servo readers 331 and no writers. The first andthird modules 302, 306 include a plurality of writers 322 and no datareaders, with the exception that the outer modules 302, 306 may includeoptional servo readers. The servo readers may be used to position thehead during reading and/or writing operations. The servo reader(s) oneach module are typically located towards the end of the array ofreaders or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some aspects, the second module 304 has a closure, while the firstand third modules 302, 306 do not have a closure. Where there is noclosure, preferably a hard coating is added to the module. One preferredcoating is diamond-like carbon (DLC).

In the approach shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used linear tape open (LTO) tape head spacing. The openspace between the modules 302, 304, 306 can still be set toapproximately 0.5 to 0.6 mm, which in some approaches is ideal forstabilizing tape motion over the second module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an approachwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this approach, thereby reducing wear on the elements in thetrailing module 306. These approaches are particularly useful forwrite-read-write applications. Additional aspects of these approachesare similar to those given above.

Typically, the tape wrap angles may be set about midway between theapproaches shown in FIGS. 5 and 6.

FIG. 7 illustrates an approach where the modules 302, 304, 306 are in anoverwrap configuration. Particularly, the tape bearing surfaces 308, 312of the outer modules 302, 306 are angled slightly more than the tape 315when set at the desired wrap angle α₂ relative to the second module 304.In this approach, the tape does not pop off of the trailing module,allowing it to be used for writing or reading. Accordingly, the leadingand middle modules can both perform reading and/or writing functionswhile the trailing module can read any just-written data. Thus, theseapproaches are preferred for write-read-write, read-write-read, andwrite-write-read applications. In the latter approaches, closures shouldbe wider than the tape canopies for ensuring read capability. The widerclosures may require a wider gap-to-gap separation. Therefore, apreferred approach has a write-read-write configuration, which may useshortened closures that thus allow closer gap-to-gap separation.

Additional aspects of the approaches shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module tape head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the approaches described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various approaches in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

As a tape is run over a module, it is preferred that the tape passessufficiently close to magnetic transducers on the module such thatreading and/or writing is efficiently performed, e.g., with a low errorrate. According to some approaches, tape tenting may be used to ensurethe tape passes sufficiently close to the portion of the module havingthe magnetic transducers. To better understand this process, FIGS. 8A-8Cillustrate the principles of tape tenting. FIG. 8A shows a module 800having an upper tape bearing surface 802 extending between oppositeedges 804, 806. A stationary tape 808 is shown wrapping around the edges804, 806. As shown, the bending stiffness of the tape 808 lifts the tapeoff of the tape bearing surface 802. Tape tension tends to flatten thetape profile, as shown in FIG. 8A. Where tape tension is minimal, thecurvature of the tape is more parabolic than shown.

FIG. 8B depicts the tape 808 in motion. The leading edge, i.e., thefirst edge the tape encounters when moving, may serve to skive air fromthe tape, thereby creating a subambient air pressure between the tape808 and the tape bearing surface 802. In FIG. 8B, the leading edge isthe left edge and the right edge is the trailing edge when the tape ismoving left to right. As a result, atmospheric pressure above the tapeurges the tape toward the tape bearing surface 802, thereby creatingtape tenting proximate each of the edges. The tape bending stiffnessresists the effect of the atmospheric pressure, thereby causing the tapetenting proximate both the leading and trailing edges. Modeling predictsthat the two tents are very similar in shape.

FIG. 8C depicts how the subambient pressure urges the tape 808 towardthe tape bearing surface 802 even when a trailing guide 810 ispositioned above the plane of the tape bearing surface.

It follows that tape tenting may be used to direct the path of a tape asit passes over a module. As previously mentioned, tape tenting may beused to ensure the tape passes sufficiently close to the portion of themodule having the magnetic transducers, preferably such that readingand/or writing is efficiently performed, e.g., with a low error rate.

Magnetic tapes may be stored in tape cartridges that are, in turn,stored at storage slots or the like inside a data storage library. Thetape cartridges may be stored in the library such that they areaccessible for physical retrieval. In addition to magnetic tapes andtape cartridges, data storage libraries may include data storage drivesthat store data to, and/or retrieve data from, the magnetic tapes.Moreover, tape libraries and the components included therein mayimplement a file system which enables access to tape and data stored onthe tape.

File systems may be used to control how data is stored in, and retrievedfrom, memory. Thus, a file system may include the processes and datastructures that an operating system uses to keep track of files inmemory, e.g., the way the files are organized in memory. Linear TapeFile System (LTFS) is an exemplary format of a file system that may beimplemented in a given library in order to enables access to complianttapes. It should be appreciated that various approaches herein can beimplemented with a wide range of file system formats, including forexample IBM Spectrum Archive Library Edition (LTFS LE). However, toprovide a context, and solely to assist the reader, some of theapproaches below may be described with reference to LTFS which is a typeof file system format. This has been done by way of example only, andshould not be deemed limiting on the invention defined in the claims.

A tape cartridge may be “loaded” by inserting the cartridge into thetape drive, and the tape cartridge may be “unloaded” by removing thetape cartridge from the tape drive. Once loaded in a tape drive, thetape in the cartridge may be “threaded” through the drive by physicallypulling the tape (the magnetic recording portion) from the tapecartridge, and passing it above a magnetic head of a tape drive.Furthermore, the tape may be attached on a take-up reel (e.g., see 121of FIG. 1A above) to move the tape over the magnetic head.

Once threaded in the tape drive, the tape in the cartridge may be“mounted” by reading metadata on a tape and bringing the tape into astate where the LTFS is able to use the tape as a constituent componentof a file system. Moreover, in order to “unmount” a tape, metadata ispreferably first written on the tape (e.g., as an index), after whichthe tape may be removed from the state where the LTFS is allowed to usethe tape as a constituent component of a file system. Finally, to“unthread” the tape, the tape is unattached from the take-up reel and isphysically placed back into the inside of a tape cartridge again. Thecartridge may remain loaded in the tape drive even after the tape hasbeen unthreaded, e.g., waiting for another read and/or write request.However, in other instances, the tape cartridge may be unloaded from thetape drive upon the tape being unthreaded, e.g., as described above.

Magnetic tape is a sequential access medium. Thus, new data is writtento the tape by appending the data at the end of previously written data.It follows that when data is recorded in a tape having only onepartition, metadata (e.g., allocation information) is continuouslyappended to an end of the previously written data as it frequentlyupdates and is accordingly rewritten to tape. As a result, the rearmostinformation is read when a tape is first mounted in order to access themost recent copy of the metadata corresponding to the tape. However,this introduces a considerable amount of delay in the process ofmounting a given tape.

To overcome this delay caused by single partition tape mediums, the LTFSformat includes a tape that is divided into two partitions, whichinclude an index partition and a data partition. The index partition maybe configured to record metadata (meta information), e.g., such as fileallocation information (Index), while the data partition may beconfigured to record the body of the data, e.g., the data itself.

Looking to FIG. 9, a magnetic tape 900 having an index partition 902 anda data partition 904 is illustrated according to one approach. As shown,data files and indexes are stored on the tape. The LTFS format allowsfor index information to be recorded in the index partition 902 at thebeginning of tape 906, as would be appreciated by one skilled in the artupon reading the present description.

As index information is updated, it preferably overwrites the previousversion of the index information, thereby allowing the currently updatedindex information to be accessible at the beginning of tape in the indexpartition. According to the specific example illustrated in FIG. 9, amost recent version of metadata Index 3 is recorded in the indexpartition 902 at the beginning of the tape 906. Conversely, all threeversion of metadata Index 1, Index 2, Index 3 as well as data File A,File B, File C, File D are recorded in the data partition 904 of thetape. Although Index 1 and Index 2 are old (e.g., outdated) indexes,because information is written to tape by appending it to the end of thepreviously written data as described above, these old indexes Index 1,Index 2 remain stored on the tape 900 in the data partition 904 withoutbeing overwritten.

The metadata may be updated in the index partition 902 and/or the datapartition 904 the same or differently depending on the desired approach.According to some approaches, the metadata of the index and/or datapartitions 902, 904 may be updated in response to the tape beingunmounted, e.g., such that the index may be read quickly from the indexpartition when that tape is mounted again. The metadata is preferablyalso written in the data partition 904 so the tape may be mounted usingthe metadata recorded in the data partition 904, e.g., as a backupoption.

According to one example, which is no way intended to limit theinvention, LTFS LE may be used to provide the functionality of writingan index in the data partition when a user explicitly instructs thesystem to do so, or at a time designated by a predetermined period whichmay be set by the user, e.g., such that data loss in the event of suddenpower stoppage can be mitigated.

As mentioned above, difficulties are encountered when attempting toincrease the number of concurrent channels in heads to enable increasein data rate per unit of tape speed, such as increase in crosstalkbetween writers when more writers are added to a given array width,increase in writer coil resistance, difficulty in managing greatercongestion in the wiring layers, higher operating temperature, etc.Various apparatuses and methods presented herein address difficultiesencountered when attempting to increase the number of concurrentchannels in heads to enable increase in data rate per unit of tapespeed.

Various approaches described below include a new head design that iscapable of reading and/or writing to magnetic media such as magneticrecording tape in multiple formats. For example, the head can writeand/or read data in both legacy and advanced formats, and in doing socan enable full backward compatibility with legacy media types. This isan important criterion for users wishing to move to a new format yethaving data stored on media in an older format.

The following description also presents solutions to the problem ofdesigning and making a magnetic tape head which increases the data rateper unit tape speed, and that is backward compatible with prior tapeformats. Various approaches also advantageously allow such head to bebuilt from two or more face-to-face modules, two or more of which aregenerally identical, and have a minimal set of transducers.

Various approaches are associated with a format for magnetic taperecording products and systems whereby data is read from and/or writtento two data bands simultaneously. Such format addresses the need for aconfiguration that enables higher data rate by allowing more activetransducer channels in use per wrap, but at the same time providesbackward compatibility to at least a previous (legacy) generation havingfewer active transducer channels in use per wrap.

Consider, for example, Linear Tape Open, 8^(th) generation (LTO-8),which is a 32 channel format that is backward compatible to LTO-5, whichis a 16 channel format. LTO was created at the outset to accommodateboth 8 and 16 channel formats, and has since moved to 32 channelformats, and thus enables a transition from 16 to 32 channels.Continuing with this example, transitioning from LTO-8 to a format using64 channels and keeping backward compatibility means at least 32 of thetransducers must align with the track layout specified by LTO-8. Totransition to 64 transducers and stay within a single data band, thepitch between channels would need to be halved. Again, this creates aplethora of problems.

In some approaches described herein, multi-faceted compatibility isachieved by preserving the legacy transducer layout that includesreaders and/or writers as well as servo readers positioned according toa legacy format, such as a format wherein data tracks in a single databand on tape are concurrently operated on. Additional transducers flankthe legacy layout and servo readers to enable writing to two or moredata bands simultaneously. When the apparatus is used with the legacyformat, the readers and/or writers arranged according to the legacyformat are used along with the servo readers adjacent thereto, but notthe readers and/or writers flanking the inner array. When operatingaccording to newer formats, the readers and/or writers in the legacytransducer layout as well as the readers and/or writers flanking thetransducers in the legacy layout are used in some aspects. For example,most or all of the transducers may align with two data bands on thetape, thereby enabling reading and/or writing to data tracks in two databands simultaneously. This effectively doubles the data rate, and avoidsthe aforementioned problems encountered when trying to compact twice thenumber of transducers into a single data band width.

FIGS. 10-16 depict an apparatus 1000, in accordance with variousapproaches of the present invention. As an option, the present apparatus1000 may be implemented in conjunction with features from any otherapproach listed herein, such as those described with reference to theother FIGS. Of course, however, the apparatus 1000 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative approacheslisted herein. Further, the apparatus 1000 presented herein may be usedin any desired environment.

Except as otherwise described herein the apparatus 1000 may beconstructed via conventional techniques modified to create the new andnovel structures described herein. Moreover, except as otherwisedescribed herein the apparatus 1000 may operate using conventionaltechniques modified as described herein, and/or as would become apparentto one skilled in the art upon reading the present disclosure.

As shown in FIG. 10, the apparatus 1000 includes a module 1002 having aninner array 1004 of data transducers on the module 1002, the transducersof the inner array 1004 being aligned along a common axis 1006 thatextends between distal ends of the module 1002. Two outer arrays 1008,1010 of data transducers are positioned to sandwich the inner array 1004therebetween.

Preferably, the arrays 1004, 1008, 1010 are positioned in the same thinfilm gap of the module, which advantageously allows simultaneousfabrication of the transducers. The arrays 1004, 1008, 1010 arepreferably aligned along the common axis 1006.

The data transducers in the arrays 1004, 1008, 1010 may be of any type.The data transducers in all arrays are preferably of the same type,e.g., all readers, all writers, piggybacked or merged reader/writerpairs, etc. Known data transducer designs may be used in variousaspects.

Moreover, any number of transducers may be present in each array, e.g.,8, 9, 15, 16, 17, 32, 33, 64, 65, 128, 129, etc. Typically, the numberof transducers in each outer array 1008, 1010 is about half the numberof like transducers in the inner array 1004.

In one aspect, the collective number of transducers in both outer arrays1008, 1010 equals the total number of transducers in the inner array1004. In another aspect, the collective number of transducers in theouter arrays 1008, 1010 is less than the total number of transducers inthe inner array 1004. For example, the inner array 1004 may have 33transducers, while each outer array 1008, 1010 has 16 transducers.

Inner servo readers 1012 are positioned between the inner array 1004 andthe outer arrays 1008, 1010. Outer servo readers 1014 are positionedtoward outer ends of the outer arrays 1008, 1010. The distance betweenthe inner servo readers 1012 corresponds to one data band width of amagnetic recording tape for which the apparatus is designed, e.g., anLTO-compatible tape. Accordingly, the inner servo readers 1012 align toa unique data band on the magnetic recording tape when the inner array1004 is being used to transduce data on a single data band.

The outer servo readers 1014 are spaced two data bands apart, i.e., adistance between the outer servo readers 1014 corresponds to two databand widths of the magnetic recording tape for which the apparatus isdesigned.

In further approaches, multiple servo readers may be positioned togetherat any of the servo reader locations disclosed herein. For example, twoor more servo readers may be present adjacent an array to enable usewith various types of servo patterns, which may be of any known and/orfuture type. In one aspect, one of the servo readers in the group ofservo readers may be a servo reader positioned in a legacy position,which corresponds to expected servo track centerlines on the tape. Inanother aspect, two servo readers in the group are centered about thelegacy position.

As depicted in FIG. 10, the inner array 1004 is positioned along acenterline 1016 of the module, the centerline being positioned at abouta center of the common axis 1006 and oriented along a tape traveldirection 1018 relative to the module 1002. However, in otherapproaches, the midpoint of the inner array 1004 may be offset from thecenterline 1016 of the module 1002. Any desired offset may be used invarious approaches.

FIG. 11 depicts one configuration of the arrays 1004, 1008, 1010 of theapparatus 1000. The pitch between data transducers 1019 in each array1004, 1008, 1010 is about the same. However, in other approaches (notshown), the pitch between the transducers in the outer arrays 1008, 1010is different than the pitch between the transducers in the inner array1004.

FIG. 12 depicts another configuration of the apparatus 1000. As shown, apitch between the data transducers 1019 in the inner array 1004 is aboutthe same as a pitch between only some of the data transducers 1019 ineach outer array 1008, 1010. For example, each of the outer arrays 1008,1010 has a debris median zone 1020 therein defined between adjacenttransducers having a greater pitch than any other adjacent pair oftransducers in the respective array 1008, 1010. The function of thedebris median zone 1020 is to prevent tape edges from rubbing againsttransducers in the outer arrays when the apparatus is used in the legacymode.

Preferably, each debris median zone 1020 is at least 1.5 times the pitchbetween adjacent pairs of transducers in the respective array (excludingthe pitch between the two transducers immediately flanking the debrismedian zone). For example, each debris median zone 1020 may be about 2times the pitch between adjacent pairs of transducers in the respectivearray (excluding the pitch between the two transducers immediatelyflanking the debris median zone). In a yet further approach, each debrismedian zone 1020 is greater than 2 times the pitch between adjacentpairs of transducers in the respective array (excluding the pitchbetween the two transducers immediately flanking the debris medianzone). Note also that the number of transducers in each outer array1008, 1010 may be reduced to accommodate the debris median zone 1020while maintaining the position of the outer servo readers 1014 to remainover the servo tracks on tape.

In some approaches, widths of at least some of the outermost datatransducers, e.g., readers, in the inner array 1004 are less than widthsof at least some of the innermost data transducers in the inner array1004. Reference is made by way of example to FIG. 13, which depictsinner array 1004 having transducer widths that progressively decreasefrom the innermost data transducers to the outermost data transducers.

In operation, with or without both outer arrays functioning, the innerservo readers 1012 read servo tracks on the tape. A controller analyzesthe servo readback signal and positions the array 1004 at theappropriate position relative to the tape so that the data transducers1019 are over the appropriate data tracks on the tape. Thus, forexample, if the tape expands and the innermost readers are centered asclosely as possible to the centers of the respective data tracks theyare intended to read, the outermost readers of inner array 1004 will beadjacent the inside edges of the data tracks they are intended to read.Conversely, if the tape contracts and the innermost readers are centeredas closely as possible to the centers of the respective data tracks, theoutermost readers of inner array 1004 will be adjacent the outer edgesof the data tracks they are intended to read. The servo controller maybe programmed to determine how to center the readers of the inner arrayon the data tracks.

In one approach, the track width of the innermost readers 1021 may beset at close to the track pitch on the tape, e.g., 0.6 to 1 times thetrack pitch. The track widths of the remaining readers progressivelydecrease from the innermost reader 1021 to the outermost reader 1023.

In another approach, the track width of the innermost readers 1021 maybe set at what it would be in a conventionally designed head, e.g.,about 0.25 to about 0.6 times the track pitch on the tape. The trackwidths of the remaining readers progressively decrease from theinnermost reader 1021 to the outermost reader 1023. The pitch (center tocenter spacing) between the readers is preferably uniform across thereader array. In another approach, the track width of the innermostreaders 1021 may be set at what it would be in a conventionally designedhead, e.g., about 0.25 to about 0.6 times the track pitch on the tape,with track widths of the remaining readers progressively decrease fromthe innermost reader 1021 to the outermost reader 1023. An illustrativetrack width of the outermost reader 1023 is in a range of 0.5 to 1micron, e.g., 0.7 micron, while an illustrative track width of theinnermost reader 1021 is in a range of 0.75 to 1.3 micron, e.g., 1.2micron. Of course, this range could be larger or smaller, with endpointsbeing higher or lower in various aspects.

The progressively narrowing width of the readers reduces misregistrationdue to mis-tracking and tape width changes. A wider reader provides alower noise signal. Particularly, making track widths of the innermostreaders wider can boost signal-to-media noise ratio (SMNR) by an amountproportional to the square root of the reader width for the centraltracks in products where the written track pitch approaches 2-3 microns.A preferred approach has reader track widths scaled linearly from widestat the innermost reader 1021 to narrowest at the outmost reader 1023.

An alternate approach has reader track widths scaled non-linearly fromwidest at the innermost reader 1021 to narrowest at the outmost readers1023. In one aspect, the reader track widths decrease progressively morepronouncedly from the innermost reader 1021 to the outmost reader 1023.

In another approach, shown in FIG. 14, adjacent sets 1402, 1404, 1406 ofmultiple readers have reader track widths that are about the same in agiven set. The track widths decrease from the innermost set 1402 to theoutermost sets 1406. Such an approach may be selected for processingconsiderations.

In all approaches, the track widths of the innermost readers arepreferably still smaller than the widths of the written data tracks sothat tape lateral transients do not create misregistration. Note thatsome overlap of the readers onto adjacent data tracks is permissible, asin an approach having filtering and/or implementing a deconvolutionscheme. Thus, some reader track widths may be as large as, or largerthan, the written track widths.

In various aspects, the widths of the transducers in the inner array1004 are scaled, e.g., as described with reference to FIGS. 13-14, whilethe widths of the transducers in the outer arrays 1008, 1010 are notscaled but rather have a generally uniform width. In other aspects, thewidths of the transducers in the inner array 1004 are not scaled, whilethe widths of the transducers in the outer arrays 1008, 1010 are scaled.In yet other aspects, the widths of the transducers in the inner array1004 are scaled, and the widths of the transducers in the outer arrays1008, 1010 are also scaled.

Accordingly, in some approaches, widths of at least some of theoutermost data transducers in each outer array 1008, 1010 are less thanwidths of at least some of the innermost data transducers in each outerarray 1008, 1010. Reference is made by way of example to FIG. 15, whichdepicts outer array 1008. In operation with both outer arraysfunctioning, the outer servo readers 1014 read servo tracks on the tape.A controller analyzes the servo readback signal and positions the arraysat the appropriate position relative to the tape so that the datatransducers 1019 are over the appropriate data tracks on the tape. Ifthe tape expands, the outermost readers of outer array 1008 may beadjacent the inside edges of the data tracks, yet the readers of theinner array (not shown) are more closely aligned with the center of thedata tracks. The servo controller can determine how to center thereaders of the inner array on the data tracks. Particularly, outer servoreaders 1014 have a very small track width compared to servo tracks, andthe controller can determine the lateral position of the arrays relativeto the tape based on the servo readback signal.

The readers of the inner array may thus be very close tocentrally-aligned with the inner data tracks, as tape lateral expansionand contraction will have an increasingly greater effect on the positionof the data tracks relative to the readers/writers of the outer arrays,and more so for outermost readers/writers of the outer arrays. Towardthe middle of the arrays, tape lateral expansion should have very littleeffect on track/reader misregistration. Accordingly, the readers can bemade wider towards the middle of the group of arrays, thereby providingan improved signal having greater signal to media noise ratio.

With continued reference to FIG. 15, inner readers of outer array 1008,preferably including at least the innermost reader 1022, have a widertrack width than at least some of the outer readers, i.e., thosepositioned between the inner readers and the ends of the array, andincluding the outermost readers 1024, which neighbors outer servoreaders 1014 in this approach. For example, the track width of theoutermost reader 1024 may be set at what it would be in a conventionallydesigned head, e.g., about 0.25 to about 0.6 times the track pitch onthe tape. The track widths of the remaining readers progressivelydecrease from the innermost reader 1022 to the outermost reader 1024.The pitch (center to center spacing) between the readers 1022 and 1024is preferably uniform across the reader array. In another approach, thetrack width of the innermost readers 1022 may be set at what it would bein a conventionally designed head, e.g., about 0.25 to about 0.6 timesthe track pitch on the tape, with track widths of the remaining readersprogressively decrease from the innermost reader 1022 to the outermostreader 1024. An illustrative track width of the innermost reader 1022 isin a range of 0.5 to 1 micron, e.g., 0.7 micron, while an illustrativetrack width of the outermost reader 1024 is in a range of 0.75 to 1.3micron, e.g., 1.2 micron. Of course, this range could be larger orsmaller, with endpoints being higher or lower in various aspects.

The progressively narrowing width of the readers reduces misregistrationdue to mis-tracking and tape width changes. A wider reader provides alower noise signal. Particularly, making track widths of the innermostreaders wider can boost signal-to-media noise ratio (SMNR) by an amountproportional to the square root of the reader width for the centraltracks in products where the written track pitch approaches 2-3 microns.A preferred approach has reader track widths scaled linearly from widestat the innermost reader 1022 to narrowest at the outmost reader 1024.

An alternate approach has reader track widths scaled non-linearly fromwidest at the innermost reader 1022 to narrowest at the outmost readers1024. In one aspect, the reader track widths decrease progressively morepronouncedly from the innermost reader 1022 to the outmost reader 1024.

Yet another approach, shown in FIG. 16, has adjacent sets 1602, 1604,1606, 1608 of readers with reader track widths being about the same in agiven set, where the track widths in a given set decrease from theinnermost set 1602 to the outermost sets 1608. Such an approach may beselected for processing considerations.

The track widths of the innermost readers are preferably still smallerthan the widths of the written data tracks so that tape lateraltransients do not create misregistration. Note that some overlap of thereaders onto adjacent data tracks is permissible, as in an approachhaving filtering and/or implementing a deconvolution scheme. Thus, somereader track widths may be as large as, or larger than, the writtentrack widths.

In one approach, the transducers of the inner array 1004 have uniformwidths while the transducers in the outer arrays 1008, 1010 have thevarying widths, e.g., as demonstrated in FIGS. 15-16.

In one approach, both the inner and outer arrays 1004, 1008, 1010 havetransducers with differing widths, e.g., as depicted in FIGS. 13-16 inany combination. For example, the innermost data transducers of theouter arrays may have a similar width as the outermost data transducersof the inner array. In another approach, the innermost data transducersof the outer arrays may have a smaller width than the outermost datatransducers of the inner array.

While various positions of the transducer arrays are shown in FIGS.10-16, the arrays may be located in other positions relative to thecenterline 1016 in various approaches. For example, positions of thearrays may be selected to ensure the tape does not extend beyond theedge of the module when in use.

In some aspects, the apparatus may include logic and/or a mechanism foradjusting the span of the module and/or the span of one or both arraysto accommodate tape and/or head expansion and/or contraction.Illustrative techniques include actively controlling tape tension, theuse of heaters and/coolers to induce expansion/contraction of themodule, piezo actuation of the module, tilting the module, etc.

As noted above with reference to FIG. 1A, the apparatus 1000 of FIGS.10-16 may include a drive mechanism for passing a magnetic medium overthe module and a controller electrically coupled to the module.

In one mode of use, the controller is configured to simultaneouslytransduce data on two data bands of the magnetic recording tape, andperform track following using at least two outer servo readerspositioned outside the arrays. For example, when a magnetic recordingtape is passed over the module 1002, at least some of the transducers ofall arrays 1004, 1008, 1010 are used reading or writing simultaneously.The outer servo readers 1014 are used for track following in oneapproach. Any type of servo pattern and/or track following technique maybe used, including conventional patterns and techniques.

In another mode of use, where all data tracks simultaneously operated onare within a single data band, the inner array is selected for use. Thecontroller is thus configured to select the inner array according to alegacy mode of operation, perform track following using the inner servoreaders 1012, and transduce data in a single data band using only theinner array 1004.

In any approach, the outer servo readers 1014 may be used for at leastskew following.

FIG. 17 depicts use of the apparatus 1000 of FIG. 10 for reading aformat where all data tracks simultaneously operated on in a given passare within two adjacent data bands. For example, when the module 1002 ispositioned at position A, the two leftmost data bands 1502, 1504 of themagnetic recording tape 1500 are operated on simultaneously using thearrays 1004, 1008, 1010. Any type of reading or writing may be performedsuch as, for example, serpentine or nonserpentine shingled writing. Asshown, the outer servo readers 1014 are each positioned above arespective servo track 1510. Also, the transducer of the inner array1004 positioned above a servo track is preferably not used.

Once the data operation is completed in data bands 1502, 1504, themodule 1002 may be moved to position B to position the arrays 1004,1008, 1010 above the rightmost data bands 1506, 1508, and the desiredoperation performed.

FIG. 18 depicts use of the apparatus 1000 of FIG. 10 for reading alegacy format where all data tracks simultaneously operated on in agiven pass are within a single data band of the magnetic recording tape1500. Operation is similar to that described with reference to FIG. 17,except only the inner array 1004 is used, and the module 1002 is movedto positions A-D to operate on each data band. Track following may beperformed using the inner servo readers 1012.

Now referring to FIG. 19, a flowchart of a method 1900 is shownaccording to one approach. The method 1900 may be performed inaccordance with the present invention in any of the environmentsdepicted in FIGS. 1-18, among others, in various approaches. Of course,more or less operations than those specifically described in FIG. 19 maybe included in method 1900, as would be understood by one of skill inthe art upon reading the present descriptions.

Each of the steps of the method 1900 may be performed by any suitablecomponent of the operating environment. For example, in variousapproaches, the method 1900 may be partially or entirely performed by atape drive or some other device having one or more processors therein.The processor, e.g., processing circuit(s), chip(s), and/or module(s)implemented in hardware and/or software, and preferably having at leastone hardware component may be utilized in any device to perform one ormore steps of the method 1900. Illustrative processors include, but arenot limited to, a central processing unit (CPU), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), etc.,combinations thereof, or any other suitable computing device known inthe art.

As shown in FIG. 19, method 1900 may initiate with operation 1902, wherea magnetic recording tape having a plurality of data bands is passedover a module according to any approach described herein. Preferredapproaches use a version of the module depicted in FIGS. 10-18.Operation 1904 includes simultaneously transducing data on two of thedata bands using the data transducers of the arrays, i.e., readingand/or writing. Track following may be performed using at least the twoouter servo readers.

In one aspect, the inner array may be selected according to a legacymode of operation. Track following is performed using the inner servoreaders adjacent the inner array. Data is transduced using only theinner array. See, e.g., FIG. 18.

Various additional operations may be performed, according to variousaspects. For example, tape tension may be adjusted, e.g., tension may beused to adjust the width of the tape to help maintain registrationbetween the transducers and the data tracks on tape. The effects oftensioning scale uniformly across the tape, making this approach veryuseful.

In another approach, the tilt of the arrays relative to longitudinalaxes of the data bands may be adjusted to alter the pitch of thetransducers as presented to the tape.

Known tape drive operations of any type may also be performed.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a computer, or other programmable data processing apparatusto produce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks. These computerreadable program instructions may also be stored in a computer readablestorage medium that can direct a computer, a programmable dataprocessing apparatus, and/or other devices to function in a particularmanner, such that the computer readable storage medium havinginstructions stored therein comprises an article of manufactureincluding instructions which implement aspects of the function/actspecified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be accomplished as one step, executed concurrently,substantially concurrently, in a partially or wholly temporallyoverlapping manner, or the blocks may sometimes be executed in thereverse order, depending upon the functionality involved. It will alsobe noted that each block of the block diagrams and/or flowchartillustration, and combinations of blocks in the block diagrams and/orflowchart illustration, can be implemented by special purposehardware-based systems that perform the specified functions or acts orcarry out combinations of special purpose hardware and computerinstructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), etc. By executable by the processor, what is meant is that thelogic is hardware logic; software logic such as firmware, part of anoperating system, part of an application program; etc., or somecombination of hardware and software logic that is accessible by theprocessor and configured to cause the processor to perform somefunctionality upon execution by the processor. Software logic may bestored on local and/or remote memory of any memory type, as known in theart. Any processor known in the art may be used, such as a softwareprocessor module and/or a hardware processor such as an ASIC, a FPGA, acentral processing unit (CPU), an integrated circuit (IC), etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

The descriptions of the various embodiments and aspects of the presentinvention have been presented for purposes of illustration, but are notintended to be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

1. An apparatus, comprising: an inner array of data transducers on amodule, the data transducers of the inner array being aligned along acommon axis that extends between distal ends of the module; two outerarrays of data transducers positioned to sandwich the inner arraytherebetween; inner servo readers positioned between the inner array andthe outer arrays; and outer servo readers positioned toward outer endsof the outer arrays, wherein widths of at least some of the outermostdata transducers in the inner array are less than widths of at leastsome of the innermost data transducers in the inner array, wherein apitch between data transducers in the inner array is about the same as apitch between at least some of the data transducers in each outer array.2. An apparatus as recited in claim 1, wherein the pitch between datatransducers in the inner array is about the same as the pitch betweendata transducers in each outer array.
 3. An apparatus as recited inclaim 1, wherein the pitch between data transducers in the inner arrayis about the same as the pitch between only some of the data transducersin each outer array.
 4. An apparatus as recited in claim 1, wherein adistance between the inner servo readers corresponds to one data bandwidth of a magnetic recording tape for which the apparatus is designed.5. An apparatus as recited in claim 4, wherein a distance between theouter servo readers corresponds to two data band widths of the magneticrecording tape for which the apparatus is designed.
 6. An apparatus asrecited in claim 1, wherein the inner array is centered on the modulebetween distal ends of the module.
 7. An apparatus as recited in claim1, wherein the collective number of transducers in both outer arraysequals the total number of transducers in the inner array.
 8. Anapparatus as recited in claim 1, wherein the collective number oftransducers in the outer arrays is less than the total number oftransducers in the inner array.
 9. An apparatus as recited in claim 1,wherein each of the outer arrays has a debris median zone thereindefined between adjacent transducers having a greater pitch than anyother adjacent pair of transducers in the respective array.
 10. Anapparatus as recited in claim 9, wherein each debris median zone is atleast 1.5 times the pitch between adjacent pairs of transducers in therespective array.
 11. An apparatus as recited in claim 9, wherein eachdebris median zone is about 2 times the pitch between adjacent pairs oftransducers in the respective array.
 12. An apparatus as recited inclaim 9, wherein each debris median zone is greater than 2 times thepitch between adjacent pairs of transducers in the respective array. 13.An apparatus as recited in claim 1, wherein widths of at least some ofthe outermost data transducers in each outer array are less than widthsof at least some of the innermost data transducers in each outer array.14. An apparatus as recited in claim 1, wherein a width of eachtransducer in each outer array is about the same.
 15. An apparatus asrecited in claim 1, wherein the transducer widths progressively decreasefrom the innermost data transducers to the outermost data transducers.16. An apparatus as recited in claim 1, wherein the data transducers aregrouped into sets of greater than one transducer, the transducers ineach set having widths that are about the same in that set, wherein thewidths decrease from the innermost set to the outermost sets.
 17. Anapparatus as recited in claim 1, further comprising: a drive mechanismfor passing a magnetic medium over the module; and a controllerelectrically coupled to the module.
 18. An apparatus as recited in claim17, wherein the controller is configured to select the inner arrayaccording to a legacy mode of operation, perform track following usingthe inner servo readers, and transduce data in a single data band of amagnetic recording tape using only the inner array.
 19. An apparatus,comprising: an inner array of data transducers on a module, the datatransducers of the inner array being aligned along a common axis thatextends between distal ends of the module; two outer arrays of datatransducers positioned to sandwich the inner array therebetween; innerservo readers positioned between the inner array and the outer arrays;and outer servo readers positioned toward outer ends of the outerarrays, wherein widths of at least some of the outermost datatransducers in the inner array are less than widths of at least some ofthe innermost data transducers in the inner array, a drive mechanism forpassing a magnetic medium over the module; and a controller electricallycoupled to the module, wherein the controller is configured tosimultaneously transduce data on two data bands of a magnetic recordingtape using all of the arrays, and perform track following using at leastthe outer servo readers.
 20. A method, comprising: passing a magneticrecording tape having a plurality of data bands over a module having: aninner array of data transducers on a module, the inner array beingaligned along a common axis that extends between distal ends of themodule, two outer arrays of data transducers positioned to sandwich theinner array therebetween, inner servo readers positioned between theinner array and the outer arrays, and outer servo readers positionedtoward outer ends of the outer arrays, wherein widths of at least someof the outermost data transducers in the inner array are less thanwidths of at least some of the innermost data transducers in the innerarray; and simultaneously transducing data on two of the data bandsusing the data transducers of the inner and outer arrays.